Real-time Corrosion Monitoring in Fossil-fuel-fired Boilers

For more information contact Kevin Davis at davis@reaction-eng.com or 801-364-6925 x23

Benefits of Corrosion Management

Reduction in unscheduled outages

Reduction in maintenance costs Tube life extension Reduction in weld

overlay coverage Improved operational

optimization – emissions vs. waterwall wastage

Quantitative assistance in fuel selection/blending decisions

Quantitative assistance in materials selection and life cycle certainty

Waterwall Corrosion

Superheater/Reheater Corrosion

Low Temperature Corrosion

Solution Approach

Evaluation of potential boiler corrosion mechanisms gas-phase sulfur species gas-phase chlorine species deposition of unreacted material

Identification of high risk locations application of CFD modeling with

integrated empirical correlations wastage measurements and/or

observations of tube failures Installation of real-time monitoring

system Data reduction including

comparisons with concurrent historical plant data

identification and validation of corrosion management strategies

“Power Plant Diagnostics Go On-Line” Mechanical Engineering, Dec 1989

Ultrasonic tube thickness

measurements

CFD-based corrosion predictions

REI Coal-Fired Boiler Corrosion Experience

Focus on impacts of firing system modifications, fuel changes, additive utilization, and operational optimization

CFD-based modeling Correlation-based approach resulting

from collaborations with EPRI and KEPRI Integrated with REI’s CFD software

(GLACIER) Real-time monitoring

Initially motivated by desire to validate modeling tools

Adaptation of an electrochemical approach in a collaborative effort with Corrosion Management (UK)

Corrosion Modeling

Prediction of fire-side corrosion through the detailed 3D modeling and advanced corrosion correlations

Waterwall and superheater corrosion mechanisms

Validated CFD Tools with Integrated Corrosion Correlations

Front Wall Rear Wall

(max = 26 mil/yr) (max = 94 mil/yr)

Side Wall Center Wall

(max = 29 mil/yr) (max = 81 mil/yr)

> 70

0

mils/yr (scale for simulations)

Real-time Corrosion Monitoring Experience

Lab-, pilot- & full-scale applications

Full-scale: Wall-fired Tangentially fired Cyclone-fired CFB

Mechanisms involving sulfur, chlorine, and bromine

Waterwall, superheater, economizer, air heater

Tube materials from inexpensive carbon steels to expensive alloys

Up to six simultaneous probes

Electrochemical Noise (EN) Corrosion Monitoring

Advantages Sensitivity Instantaneous response

allowing real-time measurement

Direct indication of corrosion

Quantitative measurement Nature of response can

indicate specific corrosion mechanism

Control and Signal Processing

Probe Hardware

Data Acquisition

Electronics

Primarily off-the-shelf components

Unique proprietary module for processing ZRA and voltage signals

Small cooling air requirements

Software

Convenient GUI-based control, monitoring, signal processing and data logging

Complete local and remote accessibility

Data Acquisition and Control

Corrosion Resistant Borders

Corroded Carbon Steel Sensor Element

Rapid Turnaround Precision Metrology

Requires late model profilometer

Modified sensor elements to provide a corrosion resistant surface for comparison

In-house software for border recognition and subtraction

Effective resolution on average corrosion depth < 0.1 micron

Quantitative Comparisons

0

2

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18

0 1 2 3 4 5 6 7 8 9 10

Profilometry Corrosion Depth (micron)

ENC

R C

orro

sion

Dep

th (m

icro

n)

F5

F7

LLL

L

L- Laboratory test in 100 MBtu/hr furnaceF5- Field test in 680 MW Coal-fired Boiler (5th floor)F7 - Field test in 680 MW Coal-fired Boiler (7th floor)

Profilometry

CFD Modeling

Lab-scale Testing

0

1

2

3

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5

6

7

8

9

10

1/26 13:40 1/26 20:20 1/27 3:00 1/27 9:40 1/27 16:20 1/27 23:00

Date/Time

S.R. = 0.90 S.R. = 0.85S.R. = 0.90S.R. = 0.95

0

100

200

300

400

500

600

3/23/2001 4:48 3/23/2001 16:48 3/24/2001 4:48 3/24/2001 16:48 3/25/2001 4:48 3/25/2001 16:48 3/26/2001 4:48

Date & Time

Tem

pera

ture

(C)

0

0.01

0.02

0.03

0.04

0.05

0.06

Cor

rosi

on R

ate

(mm

/yr)

Metal Temperature

Corrosion Rate Temperature response

Stoichiometry response

Pilot-scale Testing

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Test 1 (0 ppm) Test 2 (~25 ppm) Test 3 (~90 ppm) Test 4 (0 ppm)

Test and H2S Level

CR

/CR

max

CorrProbeKungCorr

1.5 MW Pilot-scale Coal-fired Furnace 1.6 MW Pilot-scale Coal-fired Furnace

Probe Designs

Design approaches are tailored to simulate relevant conditions

Flush Face Water-wall crowns Duct wall surfaces Stack liner surfaces

Cylindrical Superheater/Re-heater banks Economizers Air heaters

High Temperature Boiler Applications

Waterwall

Superheater

Cyclone Boiler Waterwall Start-up Response

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2

4

6

8

10

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14

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18

20

10/8/00 15:00 10/8/00 19:00 10/8/00 23:00 10/9/00 3:00 10/9/00 7:00

Cor

rosi

on R

ate

(mils

/yr)

250

300

350

400

450

500

550

Met

al te

mpe

ratu

re (d

egC

)

1 hr moving average

0

20

40

60

80

100

120

140

160

180

200

9/30/00 18:00 10/1/00 6:00 10/1/00 18:00 10/2/00 6:00 10/2/00 18:00

Cor

rosi

on R

ate

(mils

/yr

0

100

200

300

400

500

600

Met

al T

empe

ratu

re (d

egC

Steady Boiler Operation

Startup/Outage/Restart

PC Boiler Waterwall Load Response

USC Superheater Material Evaluation

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

640 660 680 700 720

Tube Metal Temperature, ºC

Cor

rosi

on R

ate,

mm

/yr

T92T91TP347HFGT122S304HHR3C

347H Metallographic Results

0

2

4

6

8

10

12

14

16

18

20

Na Mg Al Si Mn S Ca Cr Fe Zr Ni Nb Mo O

Mas

s %

Pre-Test Scale AveragePre-Test Steel AveragePost-Test Scale AveragePost-Test Steel Average

69.7 70.8 56 66.6Backscattered Electron Images of the 347H

Corrosion Element

Pre-Combustion Testing

Post-Combustion Testing

Sulfur is present in the post-test scale and steel

Nickel has been removed in the post-test scale

0

100

200

300

400

500

600

700

8/21/01 8/23/01 8/25/01 8/27/01 8/29/01 8/31/01 9/2/01 9/4/01 9/6/010

0.5

1

1.5

2

2.5

3

3.5

Corrosion Rate

Boiler Load

0

100

200

300

400

500

600

700

9/10/01 9/12/01 9/14/01 9/16/01 9/18/01 9/20/01 9/22/01 9/24/01 9/26/01 9/28/01

Date

0

10

20

30

40

50

60

70

Load

Corrosion Rate

Upper Furnace

Mid- furnace

Impact of Unreacted Fuel Deposition

Low Temperature Boiler Applications

FGD

Stack

Air Heater Exit Duct

0

50

100

150

200

250

0

0.12

0.24

0.36

0.48

0.6

16:30:00 16:45:00 17:00:00 17:15:00 17:30:00 17:45:00 18:00:00 18:15:00

Prob

e te

mp

(°F)

Cor

rosi

on ra

te, m

m/y

r

Probe A Corrosion

Probe A Temperature

0

50

100

150

200

250

0

0.12

0.24

0.36

0.48

0.6

14:20:00 14:35:00 14:50:00 15:05:00 15:20:00 15:35:00 15:50:00 16:05:00

Prob

e te

mp

(°F)

Corr

osio

n ra

te, m

m/y

r

Probe A Corrosion

Probe A Temperature

With Bromine

Without Bromine

Dewpoint Corrosion Under Oxy-firing

Dewpoint Corrosion: Impact of Bromine Additive

Oxy-firing Bituminous Coal

Dewpoint Corrosion with PRB

REI has extensive experience in the development, validation, and application of EN-based real-time corrosion monitoring including: Probe designs for waterwall, superheater, economizer, air heater

applications Environments resulting in corrosion from gas-phase and deposited sulfur,

molten sulfates, high temperature gas-phase chlorine, low temperature acid condensation

Simultaneous evaluation of multiple tube materials This experience is complemented by unique capabilities/tools

including: Advanced CFD models with integrated mechanism-specific correlations A rapid turnaround precision metrology technique Access to and experience with lab- and pilot-scale test facilities Deposit/tube characterization

Summary

Publications and Presentations

J. Beutler, K. Davis, T. Shurtz, D. Bai, R. Jafari, W. Cox “Successful Real-time Corrosion Monitoring during Co-firing of MPH Energy’s Reengineered Feedstock,” Impacts of Fuel Quality on Power Production, Snowbird, UT, October, 2014.

K. Davis, B. Adams, J. Beutler, T. Shurtz “ImpactofBromineAdditiononLowTemperatureCorrosioninAirand OxyfiredCoal Combustion,” The 39th International Technical Conference on Clean Coal & Fuel Systems, Clearwater, FL, June 2014.

K. Davis “Low and High Temperature Corrosion Associated with Pollutant Control Technologies,” Training Class for the NOx-Combustion Roundtable, Reinhold Environmental, Charlotte, NC, February 2014.

W. Cox, K. Davis, A. Fry, M. de Jong, D. Swensen “Successful real time on-line monitoring of high temperature corrosion in oxyfuel and other combustion systems,” 3rd International Oxy-Fuel Combustion Conference, Ponferrada, Spain, September 2013

A. Fry, B. Adams, T. Shurtz, K. Davis, W. Cox “Behaviour Related to Halogens for Oxycoal Retrofit of Utility Boilers,” 3rd International Oxy-Fuel Combustion Conference, Ponferrada, Spain, September 2013.

A. Fry, B. Adams, K. Davis, D. Swensen, S. Munson, W. Cox “Fire-side corrosion of heat transfer surfaces for air- and oxy-coal combustion,” 2nd Oxyfuel Combustion Conference, Yeppoon, Australia, September, 2011.

A. Fry, B. Adams, K. Davis, D. Swensen, S. Munson, W. Cox “An investigation into the likely impact of oxy-coal retrofit on fire-side corrosion behavior in utility boilers,” International Journal of Greenhouse Gas Control, 5S (2011) S179–S185.

A. Fry, B. Adams, K. Davis, D. Swensen, S. Munson, W. Cox “Fire-side corrosion of heat transfer surface materials for air- and oxy-coal combustion,” 36th International Technical Conference on Coal Utilization & Fuel Systems, Clearwater, FL, June 2011.

A. Fry, Adams, B., Davis, K., Cremer, M., Swensen, D., Munson, S., Kazalski, P., Cox, W., Oryshchyn, D., Gerdemann, S. “Topics in Oxy-Coal Retrofit of Utility Boilers Burner Principles and Fire-Side Corrosion,” The MEGA Symposium, Baltimore, MD, August 30–September 2, 2010.

K. Davis “A Real-Time Monitoring Technique for Fire-side Corrosion Characterization in Boilers” 23rd Annual ACERC Technical Conference, Provo, UT, February 2009

H. Shim, J. Valentine, K. Davis, S. Seo, T. Kim “Development of Fire-side Waterwall Corrosion Correlations using Pilot-scale Test Furnace” Fuel, 2008, 15-16, 3353-61.

H. Shim, J. Valentine, and K. Davis, S. Seo, E. Kim and T. Kim “Investigation of fire-side corrosion in a pilot-scale test furnace,” 32nd International Technical Conference on Coal Utilization & Fuel Systems, Clearwater, FL, June 2007.

Publications and Presentations (cont.)

H. Shim, J. Valentine, and K. Davis, S. Seo, E. Kim and T. Kim “Fire-side corrosion study in a coal-fired pilot-scale test furnace,” Impacts of Fuel Quality on Power Production, Snowbird, UT, October/November 2006.

K.A. Davis, T. Linjewile, J. R. Valentine, et al. “A multi-point corrosion monitoring system applied in a 1,300 MW coal-fired boiler, Anti-corrosion Methods and Materials 51 (5), 2004

K. Davis, T. Linjewile, J. Valentine, D. Swensen, D. Shino, J. Letcavits R. Sheidler, W. Cox, R. Carr and S. Harding "On-line monitoring of waterwall corrosion in a 100MW boiler with low NOx burners," The Mega Symposium: EPRI-DOE-EPA Combined Utility Air Pollutant Control Symposium, Washington, DC, August/September 2004.

K. Davis, T. Linjewile, D. Swensen, D. Shino, J. Letcavits, W. Cox, R. Carr, "A multi-point corrosion monitoring system applied in a 1300 MW coal-fired boiler." 29th International Technical Conference on Coal Utilization & Fuel Systems, Clearwater, FL, April 2004.

T. Linjewile, J. R. Valentine, K.A. Davis, N.S. Harding, W. Cox (2003) “Prediction and real-time monitoring techniques for corrosion characterization in furnaces,” Materials at High Temperature 20, 175.

K. Davis "Corrosion in solid fuel fired boilers: insight and solutions using computational fluid dynamics and electrochemical monitoring," 17th Annual ACERC Technical Conference, Salt Lake City, UT, February 2003.

K. Davis, T. Linjewile, J. Valentine and W. Cox "Prediction and real-time monitoring techniques for corrosion characterization in furnaces," 19th International Pittsburgh Coal Conference, September 2002.

K. Davis, T. Linjewile, G. Green, W. Cox R. Carr, N. Harding "Evaluation of an on-line technique for corrosion characterization in boilers," 3rd International Workshop on Life Cycle Issues in Advanced Energy Systems, Woburn, UK, June 2002.

T. Linjewile, K. Davis, G. Green, W. Cox, R. Carr, N. Harding, D. Overacker "On-line technique for corrosion characterization in utility boilers," United Engineering Foundation Conference on Power Production in the 21st Century: Impacts of Fuel Quality and Operations, Snowbird, UT, October 2001.

K. Davis, G. Green, T. Linjewile, S. Harding "Evaluation of an on-line technique for corrosion characterization in furnaces," 2001 Joint International Combustion Symposium, AFRC/JFRC/IEA, Kauai, HI, September 2001.

K. Davis, C. Lee, R. Seeley, S. Harding, M. Heap, and W. Cox "Waterwall corrosion evaluation in coal-fired boilers using electrochemical measurements," 25th International Technical Conference on Coal Utilization & Fuel Systems, Clearwater, FL, March 2000.